Two-year prospective natural history study of EYS-associated retinitis pigmentosa using adaptive optics: the KEYS study

This study was conducted to evaluate the longitudinal morphological changes in cone density (CD) in patients with the eyes shut homolog (EYS)-associated retinitis pigmentosa (RP) using adaptive optics (AO) fundus imaging and to assess its potential as a biomarker for disease progression. As a sub-analysis of the KEYS study, this prospective observational study was conducted at the Kobe Eye Center, involving 50 patients with EYS-RP; 27 eyes from 27 patients who were eligible for adaptive optics fundus imaging were included in this analysis. Ellipsoid zone (EZ) length was assessed using optical coherence tomography, and mean deviation (MD) values were obtained from Humphrey visual field testing. CD showed a significant reduction in all regions of interest as early as 6 months from baseline. In contrast, a significant decrease in EZ length was observed only at 24 months, while MD values did not exhibit significant changes throughout the observation period. AO fundus imaging demonstrated high sensitivity in detecting early structural changes in EYS-RP. These findings contribute to a deeper understanding of the natural history of the disease, and suggest that CD measurement may serve as a supplementary indicator for assessing disease progression.